The invention relates to a motor system.
The invention is based on the object of making available a motor system with thermal properties which are optimized in comparison with the prior art.
The invention solves this problem by a motor system having a stator, a rotor, a number of power modules which each have planar contact faces for dissipating heat, a control device which is designed to actuate the power modules, a housing, wherein the stator and the rotor are arranged inside the housing, and at least one heat sink. The heat sink has a number of planar contact faces which are connected in a thermally conductive fashion to respectively corresponding contact faces of the power modules. The heat sink has regions for dissipating heat, wherein a coolant flows around the regions in order to dissipate heat.
Firstly, the motor system has a stator, a rotor and typically also a motor shaft. The motor shaft is coupled in a mechanically rotationally fixed fashion to the rotor. The motor shaft defines a radial direction and an axial direction of the motor system. The axial direction is that direction in which the rotational axis of the motor shaft extends, and the radial direction is the direction radially with respect to the rotational axis of the motor shaft.
The stator can conventionally serve to generate a rotating magnetic field. The stator can have stator poles which are provided with individual windings. The stator and rotor are referred to in combination as an active part.
The motor system also has a number, for example between 2 and 20, of power modules which each have planar contact faces for dissipating heat. The power modules can be, for example, IGBT modules. The power modules can have power semiconductors which generate heat during their operation. In this respect, reference is also made to the relevant specialist literature.
The motor system also has a control device, for example in the form of a microcontroller, of a DSP or of an FPGA. The control device is designed to actuate the power modules, for example actuate them in such a way that suitable actuation voltages and/or suitable actuation currents are generated for one or more windings of the stator and/or one or more windings of the rotor. The control device can provide the function of a frequency inverter in conjunction with the power modules (and further components).
The motor system also has a housing, wherein the stator and the rotor are arranged inside the housing.
The motor system also has at least one heat sink. The heat sink has a number of planar, in particular rectangular, contact faces which are connected, in particular directly, in a thermally conductive fashion to respectively corresponding contact faces of the power modules. The number of contact faces is, in particular, identical to the number of power modules. The heat sink has regions for dissipating heat to a coolant, for example air, wherein the coolant flows around the regions in order to dissipate heat. The coolant preferably flows through the housing in the axial direction.
The assembly composed of power modules and heat sinks as well as the control device can also be arranged inside the housing.
The at least one heat sink can be embodied (provided, manufactured) separately from the housing, wherein the heat sink can be mechanically coupled, for example screwed, to the housing. The heat sink therefore forms an inlay heat sink. The motor system can further have end-side terminating pieces, for example in the form of an A end plate and of a B end plate. For this case, the at least one heat sink can be embodied (provided, manufactured) separately from the housing, wherein the heat sink can then be mechanically coupled, for example screwed, to one of the terminating pieces, for example the A end plate or the B end plate, and can be inserted therein.
The stator and the rotor can be arranged in a first axial section of the housing, and the at least one heat sink can be arranged or inserted into a second axial section, different from the first axial section, inside the housing, by virtue of the fact that the heat sink is pushed, for example, from one side of the housing into the housing and is subsequently screwed thereto.
The motor system can also have an intermediate element which is a thermal insulator (poor conductor of heat), wherein the intermediate element is arranged in the axial direction between the first axial section and the second axial section. The intermediate element can be composed, for example, from plastic. The intermediate element is connected between the two axial sections. For example, the intermediate element provides a continuous (stepless) junction for the coolant flowing in the axial direction. The intermediate element can have other functional regions which are seal-forming with respect to the adjacent axial regions, for example in the form of an annular groove for holding an elastomer seal.
The heat sink can be embodied in an annular shape, wherein the contact faces of the heat sink are arranged on an inner side of the ring, and the heat-dissipating regions of the heat sink are arranged as surface enlarging structured regions, in particular axially extending cooling fins or cooling webs, on an outer side of the ring.
The heat sink can be formed from a number (for example two) of annular segments. The annular segments can be formed, for example, as half shells.
The housing can have a first, central (inner), axially extending duct, wherein the stator and the rotor are arranged inside the first duct. The first duct can be a (circular) cylindrical duct. The first duct can be segmented axially into a number of partial ducts which can be thermally insulated from one another, for example, by means of thermal barrier layers. The housing can also have a number (for example four) of second, in particular cylindrical, axially extending ducts, wherein the second ducts surround the outside of the first duct radially, partially or completely, and wherein the second ducts form closed ducts for, in particular axially, conducting the coolant. In other words, the second ducts surround the first duct on the outside. The second ducts are connected, in particular in a heat-conducting fashion, to the outer wall of the first duct, for example by virtue of the fact that the first duct and the second ducts have to a certain extent common wall sections. The second ducts form closed, axially extending ducts for conducting the coolant, in particular in the form of cooling air. Cooling air can be blown into the ducts, for example from the outside, for example by means of a fan.
The second ducts for conducting the coolant can be continued in the end-side terminating pieces, for example the A end plate and/or the B end plate, or, for example in the case of air cooling, can conduct the coolant to the outside and therefore discharge it into the surroundings. A fan can be provided on the A side or on the B side, which fan forces air as the coolant through the second ducts or draws air therefrom, wherein on the side lying opposite the fan the air escapes again from the corresponding terminating pieces or is sucked in through the latter.
The first duct and the second ducts can extend only (exclusively) over the first axial section of the housing. For this purpose, the housing can be reworked, with the result that only one housing outer wall remains in the second axial section and the heat sink is plugged into said housing outer wall.
The housing can be manufactured by processing, for example milling, sawing, etc., one or more extruded sections or may be an extruded section. The heat sink can be manufactured, for example, by means of aluminum diecasting.
A (radial) cross-sectional area of the heat sink can constitute a regular polygon in its base shape. Owing to the regular polygon, the planar contact faces, with which the corresponding contact faces of the power modules can easily be placed in heat-conducting contact, are formed on the inner side of the heat sink.
According to the invention, the power modules which have a (macroscopically) planar contact face or bearing face for the dissipation of heat, are integrated in a thermally optimized fashion into a housing whose customary configuration does not have any (macroscopic) planar surfaces in its interior.
For this purpose, for example a base shape of the housing can be modified. For example the housing can be configured in the shape of an inwardly axially continuous polygon. Alternatively, in the interior of the housing just one defined axial section can be reworked in such a way that this axial section is configured in the shape of a polygon. For this purpose, for example a polygon can be milled into the interior of the housing.
In addition, pockets with (a planar) bearing face for the power modules can be provided in the inner wall of the housing, wherein the pockets do not completely penetrate the inner wall of the housing, i.e. are closed in the direction of the outer wall of the housing. Alternatively, continuous pockets (windows) can be provided in the housing wall in combination with additional heat sinks which can be plugged through the pockets, wherein the heat sinks have the planar bearing faces for the power modules. These heat sinks can have elements for increasing the size of the area around which the coolant flows, which elements project out of the base shape or into ducts for conducting the coolant of the housing, with the result that they do not project out of the housing. The elements can be, for example, cooling fins or hedgehog structures.
By means of the invention, the power modules can be coupled to the coolant satisfactorily in terms of thermal considerations (in this context the power module with the worst coupling is decisive) (Rth as small as possible), i.e. even a low temperature difference is sufficient to dissipate all the heat loss into the coolant. The active part with the rotor and stator of the machine and the power modules are thermally uncoupled, i.e. the capability to transport away heat between the active part and the power modules is restricted. Furthermore, a sufficiently high protection class (IP 54 or higher) is conceivable, said protection class permitting use in industrial environments, vehicles or the like.